"'This is not the end of anything, but rather the beginning of a two-year mission to pass new gun safety laws, protect children from toxic chemicals, and create more opportunities for working families in New Jersey,' he said in a statement. 'While I may not be seeking re-election, there is plenty of work to do before the end of this term, and I'm going to keep fighting as hard as ever for the people of New Jersey in the U.S. Senate.'

"Mr. Lautenberg, a Democrat who earned his fortune as a founder of the huge payroll firm Automatic Data Processing, had left the Senate once before, in 2001, but hated retirement so much that he jumped at the chance to return when the state's Democratic Party was looking for someone to replace Senator Robert Torricelli, facing an ethics investigation, on the ballot in 2002."

USA Today reports that this opens the way for Newark Mayor Cory Booker to run for the seat. The paper reports:

"Newark Mayor Cory Booker has declared his intention to run for the Senate next year, causing some awkwardness in the heavily Democratic state. Rep. Frank Pallone, a longtime congressman, wanted to run for the Senate if Lautenberg retired.

"Lautenberg suggested Booker deserved a 'spanking' for openly coveting his Senate seat and said he was sure the mayor would not be a 'lone soldier' in a 2014 race. Polls by Quinnipiac, Fairleigh Dickinson and Monmouth universities show Booker would have had a substantial lead over Lautenberg in a Democratic primary."